The present invention relates to an electric pump for the circulation of a liquid, for example in a circuit of an internal-combustion engine.
Usually the pumps for the circulation of a liquid, for example the engine coolant, are driven by the driving shaft via means for the transmission of motion, such as pulleys and/or gearwheels. These means require rolling bearings which, in turn, need to be lubricated and involve the presence of fluid-tight rotating means; any defect in the serviceability of the latter often leads the to entire assembly being put out of action. A typical drive system uses belts or gears with a fixed transmission ratio with the engine; as a result, the output and thus the power adsorbed are determined by engine speed and not by the actual requirements. Consequently, in many operating ranges, there is unnecessary excess output with an attendant waste of energy.
There are also known electric pumps of the above type, wherein the inductor and/or the armature is incorporated in the stationary body and in the impeller of the motor. These known pumps are however generally unreliable and expensive to manufacture.